72 research outputs found

    Hydrolysis-directed Vapor-phase Synthesis and Solution Processing of Nanostructured Conducting Polymers

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    Conducting polymers are a class of organic material that possesses semiconducting properties. Their unique molecular structure facilitates charge transport via delocalized π-electron network in the polymer backbone. Creating nanostructures in a conducting polymer increases its surface area to volume ratio and promotes molecular interaction at the surface of the polymer, resulting in enhanced physical and chemical properties, such as ion transfer, adsorption/desorption efficiency, and electrical conductivity. This dissertation focuses on synthesizing nanostructured conducting polymers and their composites from the vapor phase. The mechanisms in a novel synthetic strategy that utilizes iron corrosion products to initiate polymerization and template nanostructure formation is examined. Vapor-phase synthesis is carried out on both organic and inorganic substrates, and varying reaction conditions, such as temperature, reaction time, or anions in the iron(III) salt, creates a spectrum of morphologies (0D particles, 1D fibers, and amorphous films). This dissertation also presents methods for overcoming challenges in conducting polymer processing. Vapor-phase synthesized conducting polymers are fabricated into electrodes for state-of-art supercapacitors, humidity and temperature sensors, and proof-of-concept functional 3D-printed objects

    The micro-LED roadmap: status quo and prospects

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    Micro light-emitting diode (micro-LED) will play an important role in the future generation of smart displays. They are found very attractive in many applications, such as maskless lithography, biosensor, augmented reality (AR)/mixed reality etc, at the same time. A monitor that can fulfill saturated color rendering, high display resolution, and fast response time is highly desirable, and the micro-LED-based technology could be our best chance to meet these requirements. At present, semiconductor-based red, green and blue micro-LED chips and color-conversion enhanced micro-LEDs are the major contenders for full-color high-resolution displays. Both technologies need revolutionary ways to perfect the material qualities, fabricate the device, and assemble the individual parts into a system. In this roadmap, we will highlight the current status and challenges of micro-LED-related issues and discuss the possible advances in science and technology that can stand up to the challenges. The innovation in epitaxy, such as the tunnel junction, the direct epitaxy and nitride-based quantum wells for red and ultraviolet, can provide critical solutions to the micro-LED performance in various aspects. The quantum scale structure, like nanowires or nanorods, can be crucial for the scaling of the devices. Meanwhile, the color conversion method, which uses colloidal quantum dot as the active material, can provide a hassle-free way to assemble a large micro-LED array and emphasis the full-color demonstration via colloidal quantum dot. These quantum dots can be patterned by porous structure, inkjet, or photo-sensitive resin. In addition to the micro-LED devices, the peripheral components or technologies are equally important. Microchip transfer and repair, heterogeneous integration with the electronics, and the novel 2D material cannot be ignored, or the overall display module will be very power-consuming. The AR is one of the potential customers for micro-LED displays, and the user experience so far is limited due to the lack of a truly qualified display. Our analysis showed the micro-LED is on the way to addressing and solving the current problems, such as high loss optical coupling and narrow field of view. All these efforts are channeled to achieve an efficient display with all ideal qualities that meet our most stringent viewing requirements, and we expect it to become an indispensable part of our daily life

    Modern Applications in Optics and Photonics: From Sensing and Analytics to Communication

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    Optics and photonics are among the key technologies of the 21st century, and offer potential for novel applications in areas such as sensing and spectroscopy, analytics, monitoring, biomedical imaging/diagnostics, and optical communication technology. The high degree of control over light fields, together with the capabilities of modern processing and integration technology, enables new optical measurement systems with enhanced functionality and sensitivity. They are attractive for a range of applications that were previously inaccessible. This Special Issue aims to provide an overview of some of the most advanced application areas in optics and photonics and indicate the broad potential for the future

    TLC : une architecture photovoltaïque concentrée (CPV) au potentiel d’efficacité élevé à faible coût

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    Abstract: Human civilization has grown dependent on ready access to low-cost energy, but the fossil fuels that currently meet the bulk of humanity’s energy needs are causing environmental destruction, including potentially catastrophic global warming. Solar energy has to potential to halt global warming, and, if low enough in cost, to also bring the whole world’s population to a first world living standard. Silicon PV has dramatically reduced costs largely through decreasing the cost and increasing the efficiency of the silicon cells, but silicon is nearing its theoretical efficiency limits, and even if the cells were free, silicon PV would still be too expensive to meet these goals. Tandem CPV cells are roughly twice as efficient as silicon, but previous CPV designs have been unable to compete with silicon on cost in spite of the efficiency advantage. A new CPV architecture, called TLC for its trough, lens and cone concentration stages, proposed using initial concentration by a low-cost trough mirror to shrink the rest of an CPV module by 40X and thus reduce overall module costs. But before this PhD research project, TLC was only a paper study. This PhD research project was started to answer the question of whether TLC could work out as well as it appeared, or whether there were hidden flaws that precluded beating silicon PV on cost, or possibly even precluded TLC from working at all. Thesis chapter 3 details the main optical design aspects, and chapter 4 covers the design of the rest of the TLC module, including leading variations where there is more than one plausible way to achieve low cost and high reliability. The work included building a unified analytical model spreadsheet that linked known aspects of the TLC design together and estimated costs for a given design variation. Thesis chapter 5 covers the economics of the proposed design, with a focus on materials costs since these dominate PV overall costs, and a section on reliability since product lifetime strongly influences life-cycle cost. The work included building 3D-CAD models to refine the TLC design, and then the prototyping of individual parts and processes, and finally building a physical prototype of a TLC mini-module and putting it in sun. This physical confirmation was necessary because even after TLC has been “built” many times, in visualization, on paper, on spreadsheets, and then in COMSOL, until TLC was physically built, hidden flaws could arise at any time. Chapter 6 of this thesis covers the simulation and validation carried out to show that it is plausible that TLC can meet its cost targets. The conclusion of this thesis summarizes the overall project. The project was a success, producing a TLC design with high potential efficiency, very low materials cost, and low estimated process costs, with the potential to beat even the US Department of Energy’s goal for PV pricing in 2030. Ray-tracing a 3D model showed that the design could achieve high concentration with adequate acceptance angles, and tests showed that the prototyping cells were suitable for TLC’s massively parallel microcell-array receiver configuration. The project also successfully tested the proposed manufacturing process for molding semi-dense arrays of tertiary optical elements on the back of a lens tile and assembled a TLC mini module which was tested on sun at the focus of a trough mirror. Four papers have already been published, with a fifth paper accepted, as result of this work.La civilisation humaine est devenue de plus en plus dépendante d'un accès facile à une énergie à faible coût, mais les combustibles fossiles qui répondent actuellement à la majeure partie des besoins énergétiques de l'humanité causent la destruction de l'environnement, y compris un réchauffement climatique potentiellement catastrophique. L'énergie solaire a le potentiel d'arrêter le réchauffement climatique et, si son coût est suffisamment bas, d'amener également la population mondiale entière à un niveau de vie du premier monde. Les coûts de photovoltaïque (PV) à base de silicium ont été considérablement réduits en grande partie en diminuant le prix et en augmentant l'efficacité des cellules en silicium, cependant l’utilisation de silicium a ses limites d'efficacité théoriques, et même si les cellules étaient gratuites, la PV à base de silicium serait encore trop chère pour atteindre ces objectifs. Les cellules de photovoltaïque concentré (CPV) Tandem sont environ deux fois plus efficaces que celles à base de silicium, mais malgré l'avantage de leur efficacité, les architectures des années précédentes de CPV n'ont pas été en mesure de rivaliser avec le silicium en termes de coût. Une nouvelle architecture CPV, appelée TLC (Trough-Lens-Cone) utilise la concentration initiale par un miroir parabolique à faible coût combiné avec un module CPV de 40X et ainsi réduire les coûts globaux du module. Avant ce projet de recherche de doctorat, TLC n'était qu'une étude sur papier. Cette thèse a pour but de répondre à la question de savoir si l’approche TLC pouvait fonctionner aussi bien qu'elle était apparue, ou s'il y avait des défauts cachés qui empêchaient de battre le silicium PV sur le coût, ou pourrait même empêcher la TLC de fonctionner. Ce travail comprenait la construction d'un modèle de tableur unifié qui reliait les aspects connus de la conception TLC et les coûts estimés pour une variation de conception donnée. Nous présentons également la construction de modèles 3D-CAD pour raffiner la conception TLC, puis le prototypage de pièces individuelles et de processus, et enfin la construction d'un prototype physique d'un mini-module TLC qui est mis au soleil. Cette validation physique était nécessaire car même après que TLC ait été théoriquement et numériquement « construit » à plusieurs reprises soit, en visualisation, sur papier, sur des feuilles de calcul, puis dans COMSOL, avant que TLC soit physiquement construit, des défauts cachés pouvaient survenir à tout moment. La mise en œuvre de ce projet a réussi, produisant une conception TLC cohérente qui avait un rendement élevé avec un coût des matériaux très bas et des faibles coûts estimatifs de processus, avec un potentiel de battre même l’objectif du département américain de l'énergie pour la tarification du silicium photovoltaïque en 2030. Le suivi de raies (Ray-tracing) avec un modèle 3D a montré que la conception pouvait atteindre une concentration élevée avec des angles d'acceptation adéquats. Les tests ont également montré que les cellules de prototypage ont été bien adaptées à la nouvelle configuration de TLC de récepteur à matrice de microcellules massivement parallèle. Le projet a également testé avec succès le processus de fabrication proposé pour le moulage de réseaux semi-denses d'éléments optiques tertiaires à l'arrière d'un carreau de lentille. Le projet a également réussi à assembler un mini-module TLC et à tester sous le soleil avec le focus d'un miroir parabolique. Quatre articles ont déjà été publiés, avec un cinquième article accepté, à la suite de ce travail

    Compact Lens Technologies: Curved Image Sensor and Volumetric Imaging Efficiency

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    Compact image systems bring up people\u27s attention in the field of target recognition, surveillance, situation awareness or even photography. Conventional metrics assess image system based on image quality without considering systems\u27 volume. More comprehensive metrics, such as General Image-Quality Equation and the Targeting Task Performance metric, incorporates all image system components from object, lenses to detector and even imaging processing algorithm. All these key factors prohibit these metrics from being applied to image system in a convenient manner. Here, we propose a simple metric, volumetric imaging efficiency, considering both image quality and volume. Only concentrate on optical lenses enables the metric being implemented onto conventional bulk optics and flat optics efficiently. Curved image sensor with monocentric lenses shows an exceptional performance based on our metric but potentially challenging in fabrication due to conventional flat substrate process. Normally, this can be done with inorganic photodetector array and perform bending as the last step or organic photodetector being directly deposited on a curved plastic substrate. Inorganic method utilizes state-of-the-art CMOS technology but the interconnects suffer great strain and stress after bending and ultimately runs the risk of device failure while organic device ensures minimum strain, but the fabrication is not compatible with CMOS technology, thus a pattern transfer method is involved for contacts deposition. Here, we introduce both techniques and addressing their challenges. For inorganic device, several interconnect deposition methods are developed and both 1D and 2D bending test are performed to test their stretchability. For organic device, without CMOS circuity, we developed a new type of photodetector, frustrated organic photodetector (F-OPD), which enables single pixel selection by biasing device in different directions. A total of 45 devices are fabricated and perform as an input of 30X30 detectors array. A variety of noise sources are discussed and applied to each pixel. The image is then restored by color leveling and 2-points or 3-points non-uniformity correction (NUC). The results are compared with original figure as a proof of concept showing the capability of the device being extended to an array

    Understanding Quantum Technologies 2022

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    Understanding Quantum Technologies 2022 is a creative-commons ebook that provides a unique 360 degrees overview of quantum technologies from science and technology to geopolitical and societal issues. It covers quantum physics history, quantum physics 101, gate-based quantum computing, quantum computing engineering (including quantum error corrections and quantum computing energetics), quantum computing hardware (all qubit types, including quantum annealing and quantum simulation paradigms, history, science, research, implementation and vendors), quantum enabling technologies (cryogenics, control electronics, photonics, components fabs, raw materials), quantum computing algorithms, software development tools and use cases, unconventional computing (potential alternatives to quantum and classical computing), quantum telecommunications and cryptography, quantum sensing, quantum technologies around the world, quantum technologies societal impact and even quantum fake sciences. The main audience are computer science engineers, developers and IT specialists as well as quantum scientists and students who want to acquire a global view of how quantum technologies work, and particularly quantum computing. This version is an extensive update to the 2021 edition published in October 2021.Comment: 1132 pages, 920 figures, Letter forma

    The Science and Technology of 3D Printing

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    Three-dimensional printing, or additive manufacturing, is an emerging manufacturing process. Research and development are being performed worldwide to provide a better understanding of the science and technology of 3D printing to make high-quality parts in a cost-effective and time-efficient manner. This book includes contemporary, unique, and impactful research on 3D printing from leading organizations worldwide

    Polymer Processing and Surfaces

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    This book focuses on fundamental and applied research on polymer processing and its effect on the final surface as the optimization of polymer surface properties results in the unique applicability of these over other materials. The development and testing of the next generation of polymeric and composite materials is of particular interest. Special attention is given to polymer surface modification, external stimuli-responsive surfaces, coatings, adhesion, polymer and composites fatigue analysis, evaluation of the surface quality and microhardness, processing parameter optimization, characterization techniques, among others
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